The need to investigate biological samples in detail often exists in the life sciences sector. This applies especially to a wide variety of issues in biology, genetics, pharmacology, and the like. Cell division processes, for example, or the effect of a medication on cell development, can be investigated. In such investigations, the sample is typically observed and analyzed by means of a microscope.
Investigations using microscopes are preferable in other fields as well. In forensics, for example, one task is to discover, from a plurality of fibers, one deriving from a perpetrator. Further application areas encompass metallography, quality assurance, microtiter plate analysis, or pathology. All these application areas have in common the fact that a sample is preferably imaged or examined over a large region.
In this context, the microscope stage is often moved beneath the objective, or at least parts of the microscope are moved, and the sample is thereby scanned in linear or meander fashion or along another geometric trajectory. The movement of the microscope stage or of the moving part of the microscope is usually controlled electrically or electronically with the use of a control computer. The data obtained during the scanning operation are then stored on the control computer, and are made available to a user for later evaluation. The data acquired in this fashion are usually stored in a database.
With statistical investigations in particular, for example when investigating cell division, a very large quantity of data is preferably generated in order to discover a sufficient number of interesting cells. Only in this way is it possible to make sufficiently accurate statements about sample behavior in general. This involves repeatedly scanning the sample field by field along a geometric trajectory. If the number of individual fields is large, the problem exists that rapidly occurring processes can no longer be imaged with sufficient time resolution. The time span until a field is scanned again is relatively long. Processes that occur comparatively rapidly, for example in the context of cell division in biology, or fracture behavior or oxidation in metallography, therefore can no longer be observed with sufficient accuracy.
The time span between two scans of a field can be reduced by elevating the scanning rate, i.e. shortening the time required for each field; but other problems then occur. The movement of the specimen slide or of the moving part of the microscope is preferably more greatly accelerated and decelerated. A sufficient waiting time is therefore necessary to allow vibrations to decay. A steady sample is important for three-dimensional images. Tight limits are therefore placed on the speed of movement, and an upper boundary on the scanning rate exists. Individual sequences that can be assembled into a smooth movie are almost impossible in this context.
Complex regulation systems are typically used in order to image a specimen at relatively high speed and with high precision. Regulation systems of this kind, in which an electrically or electronically controllable microscope is connected to a control computer, are generally used. This control computer ensures maximally optimum movement and precise positioning of the sample. The problem still remains, however, that with mass scanning in particular, very large data quantities occur which is preferably appropriately stored. Data quantities on the order of several terabytes (TB) can quickly build up. For example, if cell division is to be observed over a period of 48 hours in an investigation of a microtiter plate having 384 scanning fields, considerable quantities of data are produced. Scanners in use at present supply images 8000×8000 pixels in size. In addition, three-dimensional data having 20 to 50 section planes are generated, and the sample is furthermore illuminated with different wavelengths. A simple calculation shows that the data quantity has already grown into the double-digit TB range. This data quantity must be not only appropriately stored, but also processed and evaluated during subsequent analysis.